Apparatus for testing reliability of interconnection in integrated circuit

ABSTRACT

In the present invention, an apparatus of testing a leakage protection reliability of an integrated circuit interconnection. The apparatus has at least one comb-like pattern, a serpentine-like pattern and means of applying a bias to the patterns and forms a maximum field region at an interconnection formed around a via, i.e., at the end of a tooth portion composing the comb-like pattern. In one structure of the present invention, the comb-like pattern is formed at one level, and the serpentine-like pattern has a plurality of unit parts corresponding to the tooth portions, respectively, and connection parts connecting the neighboring two unit parts. Each of the unit parts is formed at the same level with the comb-like pattern and spaced apart from the tooth portion by a minimum design length according to a design rule. The unit part has vias formed through an interlayer dielectric layer at the both ends of a tooth parallel part, two tooth parallel parts connected with the vias, respectively, and a length parallel part electrically connecting two tooth parallel parts.

RELATED APPLICATION

[0001] This application relies for priority upon Korean PatentApplication No. 2001-44449, filed on Jul. 24, 2001, the contents ofwhich are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to an apparatus of testing anintegrated circuit interconnection. More particularly, the presentinvention relates to a test apparatus which is suitable for testing theleakage protection reliability of an integrated circuit interconnectionhaving a high via density.

BACKGROUND OF THE INVENTION

[0003] As semiconductor devices become highly integrated, the sizes ofindividual devices and wires or interconnections become smaller. As onemethod of highly integrating the semiconductor devices, semiconductordevices may be made to have three-dimensional structures. For example,interconnections of connecting semiconductor devices are formed of aplurality of layers to have a three-dimensional structure in thesemiconductor devices.

[0004] In a very narrow region of a highly integrated semiconductordevice, it is very difficult to connect cells through a contact formedbetween an interconnection and an interlayer dielectric layer. Forexample, in a plurality of interconnection layers, a pattern has apropensity for being somewhat larger than a desired size according to aninterconnection layer. A via contact, connecting an upperinterconnection with a lower interconnection for a unified circuit, mayas a result be misaligned. This produces undesirable shorts betweencircuit nodes that should not be connected or opens between circuitnotes that should be connected.

[0005] In order to eliminate problems such as shorts or leakagecurrents, it is required to examine a leakage protection reliabilitybetween a via/contact and interconnections of various types in designsof a semiconductor device. When a circuit is designed according to agiven design rule, reliability testing of an interconnection may beperformed. That is, in relation to a pattern in a circuit, weak spotswhere a maximum field would be expected, or where a gap between patternsis at a minimum under the design rule, are artificially formed, and amaximum voltage is applied thereto. In order to increase the efficiencyof such a test, the weak spots of the designed circuit are formed intoimpressing a plurality of repeated patterns and a known voltagedifferential is applied across opposed pattern pairs. The form of thepattern may not be identical to variable and complex real worldpatterns, but typically are simplified and fixed. For testing leakageprotection reliability, standard comb-comb pattern or comb-serpentinepattern is used.

[0006] However, such a method evaluates leakage protection reliabilityonly between interconnections in one layer. This is because, in aninitial step of fabricating an integrated circuit, contacts or viasconnecting between different layers typically have a lower density thanthe density of interconnections formed within a given layer.Additionally, when a via or a contact is required, it is possible toform it at an untroubled point in the layout, i.e. a low-density circuitarea. Thus, conventional apparatus for testing an integrated circuit isuseful only for detecting problems between adjacent interconnections inone layer rather than problems of via or contact interconnectionsbetween layers.

[0007]FIG. 1 illustrates conventional apparatus for testing acomb-serpentine pattern within an integrated circuit.

[0008] Referring to FIG. 1, each of the comb patterns 10 and 20 has one(vertical) length portion, and a plurality of (horizontal) toothportions protruded from the length portion at the same circuit layerlevel with the length portion. The tooth portions are orthogonal to thelength portion, parallel to one another and repeated, thereby having thesame length. In a test apparatus, a pair of comb patterns 10 and 20 arealigned facing each other, with the tooth portions of one comb patterninterleaved with tooth portions of the other comb pattern. A serpentinepattern 30 is formed between the pair of comb patterns. Through the pairof comb patterns, the serpentine pattern 30 passes parallel to andbetween the tooth portions and turns 180° as illustrated in a regionbetween the length portion of one comb pattern and the end of the toothportion of the other comb pattern. Maximum potential differences areimpressed around the ends of the tooth portion and the neighboring partsof the serpentine pattern. Since a maximum electric field 40 islocalized at every end of the tooth portions, there are plural maximumelectric fields 40. When neither leakage nor shorts are detected at theevery maximum electric field 40, the design of a semiconductor deviceexhibits stability and reliability. A minimum design length (spacing orgap) is labeled “D”.

[0009] However, conventional apparatus for testing a leakage or a shortgenerated between interconnection layers may take the alternative formin FIG. 2. In this form, two conductive layers 50 and 60 are formed andone interlayer dielectric layer 70 is interposed therebetween. A biasvoltage is applied between two electrodes 80 formed at the conductivelayers. The form works for testing the reliability of an interlayerdielectric layer, but is too simplistic to detect real world problemsrelated to a via or a contact according to multilayered interconnectionsof a semiconductor device. Thus, in case of a via or a contact open orshort problem in a relatively simple semiconductor device having fewvias or contacts, the problem is diagnosed by an empirical method oftrial and error.

[0010] As semiconductor devices become extremely highly integrated, andinterconnections become multilayered, the density of vias or contactsincreases. A short or a leakage current may be generated between a viaand a neighboring interconnection. However, in a highly integratedsemiconductor device, a small difference in process conditions mayproduce a large difference in results or effects. For example, if adifferent method is used to form a via hole and to fill the via holewith a conductive material, or if a different conductive material isused, a formed via may have a different characteristic with respect tothe leakage current or the short.

[0011] For more specific examples, in an integrated semiconductordevice, copper is used for an interconnection and a via to reduceresistance of an interconnection or a contact. But, when the copper isprocessed, the processed surface of copper or copper oxide tends to berough. Thus, the use of copper may produce a narrow interconnection gapdue to rough surfaces and other surface irregularities. The result is ahigh probability of failure, in comparison with other interconnectionmetal having the same interconnection gap.

[0012] Additionally, when copper is used, a dual damascene process isgenerally employed because of difficulty in patterning. When the aspectratio of the via hole is increased, a barrier layer is formed at thesurface of the via hole by employing a sputtering method before fillingthe via hole with metal. But, the barrier layer is not well stacked atan edge where the sidewall and the lower surface of the via hole areconnected, so that the copper of high conductivity may make undesirablecontact with a neighboring silicon oxide layer, and a leakage or aninsulation breakdown may occur more frequently near the bottom of thevia than in other regions.

[0013] The leakage or the short may have various causes. If there are alot of problem spots, it is difficult to locate the failed spots and tocorrect them. Thus, without a systematic test, it is difficult to knowwhether a leakage or a short may occur between a via and a neighboringinterconnection in a semiconductor device. Consequently, a systematicand operational method is needed to detect such via problems in adesigned semiconductor device. In order to realize a solution, a testapparatus having a specific pattern is required, in which a design ruleof a related semiconductor device is reflected and problem areas betweenvias and neighboring interconnections are discovered and avoided.

[0014] Despite having different objects and effects, U.S. Pat. No.6,054,721 disclosed that one pattern of an apparatus of testing aleakage protection reliability between plane patterns may be changed.The idea is to evaluate alignment between patterns of different levels.In this case, a via is formed at an end of a tooth portion in a combpattern, so that the end of the via is located between lower patterns ofa different level. Thus, this case may be used for indicating a problemwhen an electric field is concentrated around the via. But, thedisclosed apparatus would not indicate when the electric field wasconcentrated on the interconnection around the via.

SUMMARY OF THE INVENTION

[0015] Thus, it is an object of the present invention to provide a testapparatus of evaluating problem spots in cases where an electric fieldis concentrated on an interconnection around a via in a denselypatterned circuit having multilayered interconnections.

[0016] It is another object of the present invention to provide a testapparatus which may easily and effectively detect a problem spot of aleakage or a short between vias and interconnections in multilayeredinterconnections.

[0017] It is still another object of the present invention to provide atest apparatus which may systematically and operationally detect problemspots of leakage currents or shorts between vias and interconnections inmultilayered interconnections.

[0018] The present invention is directed to a test apparatus. Theapparatus includes a comb-like pattern (hereinafter, simply, combpattern) and a serpentine-like pattern (hereinafter, simply serpentinepattern) having vias, and applies a bias voltage to the patterns to forma spot where an electric field is concentrated, at an interconnectionformed around vias, i.e., at the end of a tooth portion of the combpattern.

[0019] In a first aspect of the present invention, at least one combpattern has one straight length portion and a plurality of toothportions protruding from the length portion, parallel with one anotherand having the same length. The serpentine pattern has a plurality ofunit parts and connection parts. One unit part corresponds to one toothportion and surrounds the one tooth portion. The connection partconnects the unit parts. Each of the unit parts has two tooth parallelparts. Each tooth parallel part is formed at the same level with thecomb pattern, parallel with and spaced apart from the tooth portion by aminimum design length according to a design rule.

[0020] But in case that the width of the via is wider than that of thetooth parallel part, the spaced distance may be wider. Also, the unitpart is formed at a level different from that of the comb-like patternand an interlayer dielectric layer is interposed between the levels ofthe unit part and the comb pattern. The unit part also includes a lengthparallel part and two vias. The length parallel part connects the endsof the two tooth parallel part and the vias connect the ends of thetooth parallel parts with the both ends of the length parallel partthrough the interlayer dielectric layer. The via is spaced apart fromthe end of the tooth portion by the minimum design length.

[0021] In a plan view of the unit part, the length parallel part and thetooth parallel part meet at right angles to each other. The connectionpart connects the neighboring two tooth parallel parts to electricallyconnect the two unit parts and to form the serpentine pattern. Theconnection part may be formed at the same level with the length parallelpart and is connected with the tooth parallel part through a via as thetooth parallel part is connected with the length parallel part. Means ofapplying a certain bias voltage is included in the test apparatus,thereby generating a potential difference between the two patterns.

[0022] In the first aspect of the present invention, in a top plan view,the end of the tooth portion of the comb-like pattern is overlapped withthe length parallel part connecting the ends of the two tooth parallelparts or located within the minimum design length deviation from thelength parallel part.

[0023] The patterns may be formed of different conductive materialsaccording to levels. The conductive material may be of a metal and ametal, a metal silicide and a semiconductor such as a doped polysilicon.The via may be formed of a material different from a conductive materialof the upper level, or of another material of another level.

[0024] The tooth parallel part is longer than the length parallel partor the connection part at least by the minimum design length accordingto a design rule. Also, the length portion should be spaced apart fromthe connection part more than by the minimum design length.

[0025] According to a second aspect of the present invention, twocomb-like patterns are set up together with one serpentine pattern. Thatis, one additional comb pattern is added in the first aspect having onecomb pattern and one serpentine pattern. Two comb patterns are facingeach other. Tooth portions of the additional comb pattern are runningparallel with and interleaving with those of the original comb pattern.

[0026] Length portions and tooth portions of the two comb patterns areformed at the same level. The connection part of the serpentine patternin the first structure has a level different from the tooth parallelpart in the second structure, and is electrically connected with thetooth parallel part through a via formed at the end thereof in the firststructure. The end of the tooth portion of the additional comb patternis located at the central position between the ends of the two toothparallel parts under the connection part and laterally spaced apart fromthe ends thereof. But, where the width of the via is wider than that ofthe tooth parallel part, the spaced distance may be wider. Also, the endof the tooth portion in the additional comb pattern is located withinthe minimum design length deviation from the central position betweenthe ends of the neighboring two length parallel parts under theconnection part.

[0027] Thus, in the second structure, the length parallel part may becalled the connection part, since the function and component of theparts are identical with each other. The tooth parallel part is parallelto the tooth portion of the additional comb pattern. The vias are formedat the turning points where the length parallel parts or the connectionparts meet the tooth parallel parts.

[0028] The additional comb pattern may have the same shape as theoriginal comb pattern, thus overlapping it. Alternatively, theadditional comb pattern may be different in length from the toothparallel part, width and material thereof. Additionally, the length ofthe connection part may be different from that of the length parallelpart.

[0029] The second structure may be defined independently withoutrelation to the first structure. That is, in the second structure, atleast a pair of comb patterns are included. Each of the comb patternshas one straight length portion, and a plurality of tooth portionsprotruding from the length portion, the tooth portions being parallelwith one another and having identical lengths. The two comb patternsface each other at the same level and the tooth portions of the leftcomb pattern run parallel with and through those of the right combpattern. The second structure includes one serpentine pattern comprisingtooth parallel parts, first length parallel parts, second lengthparallel parts, and vias.

[0030] The tooth parallel parts are formed at the same level with thepair of comb patterns, spaced apart from the neighboring tooth portionsby a given distance and parallel therewith. The first length parallelpart is present at a level spaced from the level of the comb patterns byan interlayer dielectric layer and connecting the ends of the two toothparallel parts adjacent the comb pattern in the left or right side ofthe serpentine pattern. The second length parallel part is present at alevel spaced from the level of the comb patterns by an interlayerdielectric layer and connects the ends of the two tooth parallel partsadjacent to the comb pattern in the right or left side of the serpentinepattern. The vias connect the ends of the first and second lengthparallel parts with both ends of the tooth parallel part through aninterlayer dielectric layer, respectively, at both ends of the toothparallel part.

[0031] Additionally, the second structure has means of applying acertain bias to the comb pattern and the serpentine pattern to generatea potential difference therebetween. The second length parallel partcorresponds to the connection part in the first structure but is notpresent at the same level.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 illustrates a schematic plan view showing conventionalapparatus of testing a comb-serpentine pattern as a typical example of atest integrated circuit.

[0033]FIG. 2 illustrates a concept diagram showing conventionalapparatus of testing a problem spot of leakage current or short betweeninterconnection layers.

[0034]FIG. 3 illustrates a partial top plan view of a part in anembodiment where a comb pattern and a serpentine pattern are providedaccording to a first structure of the present invention.

[0035]FIG. 4 illustrates a partial isometric view selectively showing apart which will be repeatedly formed, in the same embodiment with thatof FIG. 3.

[0036]FIG. 5 illustrates an electric field profile showing a state whena bias voltage is applied to a terminal of each pattern in the sameembodiment with FIG. 4.

[0037]FIGS. 6 and 7 illustrate electric field profiles showing stateswhen a bias voltage is applied to a terminal of each pattern incomparative examples of the present invention.

[0038]FIG. 8 illustrates a partial top plan view of an embodiment wherea comb pattern and a serpentine pattern are provided according to asecond structure of the present invention.

[0039]FIG. 9 illustrates a partial perspective view selectively showinga part which will be repeatedly formed, in the same embodiment with thatof FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0040] The present invention will now be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. In the attached figures, the distance between components and sizesthereof may be exaggerated for clarity.

[0041] Embodiment 1

[0042]FIG. 3 illustrates a partial top plan view of a part in anembodiment where a comb pattern and a serpentine pattern are providedaccording to a first structure of the present invention.

[0043]FIG. 4 illustrates a partial perspective view of parts which willbe repeatedly formed, in an embodiment having the same partial plan viewwith FIG. 3, i.e., a tooth portion 120 and a connected length portion110 of a comb pattern 100, and a neighboring unit part 340 and aconnection part 350 of a serpentine pattern.

[0044] Referring to FIGS. 3 and 4, in the present embodiment 1, thetooth portion 120 of the comb pattern 100 is located at the centralposition between vias 330 formed at the ends of tooth parallel parts 310of the serpentine pattern. The vias 330 extend to an upward directionfrom the ends of the tooth parallel parts 310, respectively, and thetooth parallel parts 310 are laterally spaced from the tooth portion 120by a minimum design length ‘D’ according to a design rule in asemiconductor device for test. The vias 330 are wider than the toothparallel part 310. Generally, the periphery of a via bottom tends to beweakest, so that the possibility of leakage is intimately related withthe distance between the periphery of the via bottom and the neighboringinterconnection pattern. If the width of the via 330 were identical withthat of the tooth parallel part 310, and if the via 330 were exactlyaligned with the tooth portion 310, the tooth parallel part 310 would bespaced laterally from the tooth portion 120 by the minimum design length‘D’.

[0045] Additionally, in FIG. 3, the end of the tooth portion 120 seemsto be overlapped with a length parallel part 320 connecting the ends ofthe tooth parallel parts 310 at which the vias 330 are formed. Those ofskill in the art will appreciate from FIG. 4 that, while overlapped inplain view of FIG. 3, nevertheless the end of the tooth portion 120 islocated with the minimum design length ‘D’ deviation from the lengthparallel part 320. If the end of the tooth portion 120 is spaced toomuch apart from the length parallel part 320 or extends beyond the part320, a maximum field region 600 is not formed around the neighboringinterconnection of the via 330, i.e., around the end of the toothportion 120.

[0046] The tooth parallel part 320 is longer than the length parallelpart 310 or the connection part 350 at least by a minimum design lengthaccording to a design rule. The length of the tooth parallel part 310 isless than that of the tooth portion 120 by the distance ‘S’. Thedistance ‘S’ is preferably longer than the minimum design length ‘D’ andconventionally several times thereof, so that a big electric field isnot formed between the length portion 110 and the connection part 350.

[0047] The connection part 350 of the serpentine pattern is present at alower interconnection layer under an interlayer dielectric layer, i.e.,at the same level with the tooth parallel part 310. The both ends of theconnection part 350 are directly connected with the ends of the toothparallel parts at the position of the via 330.

[0048] The present embodiment typically would include pluralinterconnected instances of the illustrated parts in FIG. 4. Althoughnot shown in the drawings, pads are formed at certain ends of the combpattern and the serpentine pattern for applying a defined bias voltagein a subsequently formed test apparatus. When power is supplied to thepads, a potential difference develops between the comb pattern and theserpentine pattern.

[0049] In a method of forming the first structure like FIG. 4, a lowerconductive layer is stacked using a semiconductor material such as animpurity-doped polysilicon, using a metal such as copper, or using adual layer of a semiconductor and a metal silicide, on a semiconductorsubstrate. This is patterned to form a length portion and a toothportion in the comb pattern and a connection part and a tooth parallelpart in the serpentine pattern. When a lower interconnection ispatterned, an interlayer dielectric layer is formed thereon. Theinterlayer dielectric layer may be formed of a CVD (chemical vapordeposition) silicon oxide layer which is generally used in asemiconductor device. A planarization process is preferably performed. Apatterning process is performed to form a groove for a length parallelpart composing an upper interconnection pattern, to a certain depth,through the interlayer dielectric layer. A via hole is formed through apart of the groove to expose the ends of the tooth portion at the lowerinterconnection pattern.

[0050] A conductive barrier layer is thinly formed at the substratewhere the via hole is formed. The barrier layer is formed of atitanium/titanium nitride by employing a sputtering method. Then, acopper seed layer is stacked by a CVD method, and a bulk copper layerfills the groove and the via hole by employing an electroplate method.The copper layer and the barrier layer, which are formed on theinterlayer dielectric layer, are eliminated by a CMP (chemicalmechanical polishing) process. Thus, the via and the upperinterconnection are formed of the same material layer. Alternative tothe above dual damascene process, other processes may be employed. Thatis, a via hole is only formed through an interlayer dielectric layer anda via plug fills the via hole. A distinct conductive layer is stackedand patterned to form an upper interconnection pattern.

[0051]FIG. 5 illustrates a plan view showing a field profile or amaximum field part by simulation of the same parts of FIG. 4, when adefined voltage differential is applied between a serpentine pattern anda comb pattern. The ends of the tooth parallel parts 310 are connectedwith the length parallel part 320 through the vias 330. The end of thetooth portion 120 is present between the ends of the tooth parallelparts 310 under the length parallel part 320. Maximum field region 341corresponding to a relative electric field strength of approximately18˜21 appears around tip parts of the end of the tooth portion 120.Other electric field regions 343, 345, 347, and 349 corresponding to therelative electric field strengths sequentially appear to surround higherfield regions. Through the analysis with respect to the figures, it ispossible to know whether a failed problem spot is generated at theregions having a plurality of vias spaced by a design length in asemiconductor device. Also, it is possible to increase a reliability ofa semiconductor device by testing a design thereof.

COMPARATIVE EXAMPLE 1

[0052]FIG. 6 illustrates a plan view showing an electric field profileor a maximum field part by simulation when a certain bias is appliedbetween a serpentine pattern and a comb pattern, in a comparativeexample for being compared with the example 1. In FIG. 6, the end of thetooth portion 120 is spaced apart from the length parallel part 320 morethan by the minimum design length ‘D’. The maximum field strength in thefirst embodiment is approximately 18˜21 at the maximum field region 341like FIG. 5, but the present comparative example has the maximum fieldstrength of only approximately 14˜16 at the maximum field region 351.

COMPARATIVE EXAMPLE 2

[0053]FIG. 7 illustrates a plan view showing an electric field profileby simulation when a certain voltage is applied between a serpentinepattern and a comb pattern. In FIG. 7, the end of the tooth portion 120exceeds the position of the length parallel part 320 more than by theminimum design length ‘D’. The present comparative example has themaximum electric field strength of only approximately 10˜12 at themaximum field region 361 in comparison with the value of approximately18˜21 in the first embodiment.

[0054] Embodiment 2

[0055]FIG. 8 illustrates a partial top plan view showing a part in asecond embodiment, in which two comb patterns 200 and 400 and oneserpentine pattern 300 are provided according to a second structure. Inthe present embodiment, one comb pattern 400 is further placed laterallyfrom the serpentine pattern at the opposite position of the originalcomb pattern 200. The serpentine pattern 300 also acts as forming anelectric field with respect to the additional comb pattern 400.

[0056]FIG. 9 illustrates a partial isometric view showing parts whichwill be repeatedly formed, in an embodiment having the same partial planof FIG. 8.

[0057] Referring to FIGS. 8 and 9, the length portions 210 and 410, andthe tooth portions 220 and 420 of the two comb patterns 200 and 400, andthe tooth parallel part 310 of the serpentine pattern 300 are formed ata lower interconnection layer under an interlayer dielectric layer. Theconnection part 350 and the length parallel part 320 of the serpentinepattern 300 are formed at an upper interconnection layer over theinterlayer dielectric layer. The parts illustrated in FIG. 9 arerepeatedly connected with one another to form a core part of a testapparatus.

[0058] In the embodiment 2, the tooth portions 220 and 420 are locatedat the central positions between the tooth parallel parts 310 under theconnection parts 250 and the length parallel parts 320, respectively,and the ends of the tooth portions 220 and 420 are laterally spacedapart from the neighboring vias 330 by the minimum design lengths. InFIG. 8, the end of the tooth portion 220 overlaps the length parallelpart 320, and the end of the tooth portion 420 overlaps the connectionpart 350. The tooth parallel parts 310 should be longer than the lengthparallel parts 320 and the connection parts 350 at least by the minimumdesign length according to a design rule. When the length of the toothparallel part 310 is subtracted from that of the tooth portion 420 inthe additional comb-like pattern 400, the remnant length should belonger than the minimum design length according to the design rule andpreferably several times thereof, so that an excessive electric field isnot formed between the length portion 410 and the connection part 350.

[0059] Although the illustrated parts in FIG. 9 are rotated 180° on avertical axis ‘K’, the rotated patterns have the same shape with theoriginal patterns, i.e. the patterns are symmetric. Thus, in the presentembodiment, the length parallel part 320 is connected with a toothparallel part 310 through an additional via 360 and acts as a kind ofthe connection part 350. The connection part 350 and the length parallelpart 320 are formed at the same upper interconnection layer over theinterlayer dielectric layer. Also, one serpentine pattern 300 is usedfor forming an electric field between two comb patterns.

[0060] Except for these differences in the level of the length parallelpart 320 and the shape of the entire structure, the present embodimenthas similarities with the embodiment 1, since parts are repeatedlyconnected and the electric field may be localized around the end of thetooth portion 220 or 420 present between two neighboring vias 330 or 360under the length parallel part 320 or the connection part 350. Anapparatus for applying a bias voltage should be able to apply a certainbias to the additional comb pattern 400. Thus, all details, related tothe comb pattern 200 or 400 and the serpentine pattern 300, may beidentical with the embodiment 1. The tooth parallel part 310 is requiredto be much longer than the connection part 350, so that two collectivevias 330 don't affect the two opposite collective vias 360. The secondstructure of the present embodiment 2 has an advantage in that astructure of forming two neighboring vias 330 or 360 may be more highlyintegrated.

[0061] However, differently from the present embodiment, tooth portions220 and 420 in the two comb patterns 200 and 400, composing the secondstructure of the present invention, may have different lengths ordifferent widths from each other to the exclusion that tooth portions220 and 420 are sufficiently longer than the tooth parallel part 310.And the lengths of the tooth parallel part 310 and the connection part350 may be different. In this case, when the patterns are rotated 180°on the vertical axis ‘K’, the rotated patterns are not identical withthe original patterns.

[0062] According to the present invention, out of problems inducedaround a via and a neighboring interconnection according to multilayeredinterconnections and a narrow gap between patterns in a semiconductordevice, with respect to the case in which an electric field is localizedaround an interconnection adjacent to a via, it is possible to find outa failed or problem spot such as a leakage current or a short easily andeffectively by using a systematic and operational test apparatus.

[0063] While the invention has been shown and described with referenceto a certain preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. Apparatus for testing a leakage protectionreliability of an integrated circuit interconnection, comprising: atleast one comb-like pattern comprising one straight length portion, anda plurality of tooth portions; one serpentine-like pattern comprising aplurality of unit parts and at least one connection part; and means ofapplying a defined bias voltage between the comb-like pattern and theserpentine-like pattern to generate a potential difference between thetwo patterns, wherein the plurality of tooth portions protrude from thelength portion, substantially parallel with one another and havingsubstantially the same lengths, wherein each of the unit partscomprises: two tooth parallel parts laterally spaced apart from theneighboring tooth portions by a certain distance, and extendingsubstantially parallel therewith; a length parallel part formed at alevel different from the level of the comb-like pattern and connectingthe ends of the two tooth parallel parts and forming turning points withthe tooth parallel parts; and two vias connecting the ends of the twotooth parallel parts with the both ends of the length parallel partthrough an interlayer dielectric layer and spaced apart from the end ofthe neighboring tooth portion by a minimum design length according to adesign rule, and wherein the connection part connects the ends of theneighboring two tooth parallel parts for connecting the two unit parts.2. The apparatus as claimed in claim 1, wherein: the end of the toothportion is located within the minimum design length deviation from thelength parallel part connecting the two vias in a top plan view; and theconnection part is spaced apart from the length portion at least by theminimum design length.
 3. The apparatus as claimed in claim 1, whereinthe connection part is formed of the same material with the toothparallel part at the same level.
 4. The apparatus as claimed in claim 1,wherein the length portion, the tooth portion and the tooth parallelpart formed at the same level, and wherein the length parallel partformed at a different level, are composed of different materials.
 5. Theapparatus as claimed in claim 1, wherein the tooth parallel part islonger than the length parallel part or the connection part at least bythe minimum design length.
 6. The apparatus as claimed in claim 1,wherein the connection part is formed at a different level spaced fromthe two tooth parallel parts by the interlayer dielectric layer, andboth ends of the connection part are connected with the ends of the twotooth parallel parts by vias through the interlayer dielectric layer. 7.The apparatus as claimed in claim 1, further comprising an additionalcomb-like pattern having the same components with the comb-like patternat the opposite position of the comb-like pattern, wherein: the end ofthe tooth portion of the additional comb-like pattern is located at thecentral position between the two tooth portions of the comb-like patternunder the connection part, and laterally spaced from the neighboring twovias by the minimum design length; and the means of applying a bias iscapable of applying a defined bias voltage also to the additionalcomb-like pattern.
 8. The apparatus as claimed in claim 7, wherein: theend of the tooth portion of the additional comb-like pattern is locatedwithin the minimum design length deviation from the connection partconnecting the two vias formed at the ends of the tooth parallel parts;and the connection part is laterally spaced apart from the neighboringlength portion at least by the minimum design length in a top plan view.9. The apparatus as claimed in claim 7, wherein the comb-like patternand the additional comb-like pattern are different in length and widthof the tooth portion from at least one of the length of the toothportion and the width of the tooth portion.
 10. The apparatus as claimedin claim 7, wherein the length parallel part has a length different fromthe length of the connection part.
 11. Apparatus for testing a leakageprotection reliability of an integrated circuit interconnection,comprising: a pair of comb-like patterns, wherein each of the comb-likepatterns has one straight length portion and a plurality of toothportions, and wherein the pair of patterns face each other, aserpentine-like pattern comprising tooth parallel parts, first lengthparallel parts, second length parallel parts, and vias; and means ofapplying a defined bias voltage at the comb-like pattern and theserpentine-like pattern to generate a potential difference between thetwo patterns, wherein the tooth portions having the same lengthsprotrude from the length portion, substantially parallel with oneanother, running substantially parallel with and interleaving with theneighboring tooth portions of the other comb-like pattern; wherein thetooth parallel parts are formed at the same level with the pair of thecomb-like patterns, spaced apart from the neighboring tooth portions bya defined distance and extending substantially parallel therewith; thefirst length parallel part is present at a level spaced from the levelof the comb-like patterns by an interlayer dielectric layer andconnecting the ends of the two tooth parallel parts adjacent to thecomb-like pattern in the left or right side of the serpentine-likepattern; the second length parallel part is present at a level spacedfrom the level of the comb-like patterns by an interlayer dielectriclayer and connecting the ends of the two tooth parallel parts adjacentto the comb-like pattern in the right or left side of theserpentine-like pattern; and the vias connect the ends of the first andsecond length parallel parts with the both ends of the tooth parallelpart through an interlayer dielectric layer at the both ends of thetooth parallel part.